The design and manufacturing of highway snowplow equipment have not gone through many modifications or improvements since their commercial production. Even with a consistent weight problem, snowplow equipment designs have always called for steel materials to meet strength and rigidity requirements. In some cases, in order to reduce weight, steel snow plows have been provided with openings or their lower blades have been made of plastics material.
Up to now, the conventional snowplow equipment used on highways has faced operational problems and design defects affecting fuel consumption, handling, power consumption and chassis dynamics. For example, a typical snowplow equipment presently used by the Quebec Ministry of Transportation has the following weight problems: it represents one extra metric ton on the total weight of the vehicle and one and a half extra metric tons on the front axle of the vehicle. Since snowplows operate under a variety of hazardous conditions, such as wet and icy roads, the extra weight on the front axle (with the plow up)generates serious handling and driving conditions and, even more when the salt-sand spreader used with the road vehicle is almost empty.
Therefore, the multi-purpose snow removal vehicle operating on a highway suffer problems of overload on front axles and are subjected to high levels of constraints so that important modifications must be brought to the front chassis, to the front axle and to the tires.
The excessive weight and high rigidity of snowplow equipments, made of steel, have therefore resulted in requiring reinforcement and over-dimensioning of the front chassis, of the front axle and of the tires. These modifications are partly due to the energy which is transmitted by the snowplow equipment. The only mechanism which is presently available to reduce the impact energy when the wear blade of the snowplow contacts a severe obstacle consists of a triangular pivot device coupled to a coil spring, the function of which is to deform upon impact. However, it has been regularly observed that such pivot device is not satisfactorily functional because of its considerable inertia or, in other words, its slow reaction response. Therefore, in response to an impact due to high speed, the device is slow to react, which results in a major portion of the impact energy to be directly transmitted from the front plow to the vehicle chassis before the latter has had time to react thereby causing, in some cases, important damages to one or more of the structural components of the vehicle.
Therefore, the construction of present snow removal equipments is totally rigid, using steel, the density of which is in the order of 7.8. There results, in addition to a heavy weight equipment, an excess weight on the front axle as well as a reduction on the rear axle, the function of which is to provide traction. This traction problem is amplified more particularly in the case of a snow covered, or icy, road. The snowplow vehicle is therefore rendered less efficient by this reduction of weight on the rear axle, this being amplified by an overload on the front axle, the function of which is to direct the vehicle.
Presently, many snowplow vehicles are used for two purposes: one is snow removal, the other is abrasive spreading. In the case where the vehicle is equipped with an abrasive spreader, it is mainly used in conditions of highly icy surfaces, which renders its maneuver or driving very risky when conditions of axle weight distribution described above exist. The important cantilever configuration of a snow removal equipment, made of steel, at the front of the vehicle further reduces its maneuverability and traction when the spreader is empty. Furthermore, weight reduction on a snowplow equipment becomes an important factor to satisfy the regulations concerning loads on road surfaces while rendering the vehicle more maneuverable and safer.
Presently, a complete snowplow equipment weights about 3,450 Kg which is distributed as follows: 1,050 Kg on the snowplow, 700 Kg on the side wing and 1,700 Kg on the harness and thrust chassis of the plow and the side wing.
When the snow plow and the side wing are in the up position, the results is the following; an additional weight of 2460 Kg on the front axle and a reduction of 530 Kg on the rear axle. This weight distribution conditions prevail more particularly when the snow plow vehicle spreads salt and sand on icy road conditions when there is no snow removal.
The use of steel for the construction of these components automatically results in it being subjected to rust or corrosion, which is a chemical attack phenomenon particular to the environment in which the equipment is used. The snow plow and the side wing are also exposed to abrasion due to cumulative sand dispersed in snow. The abrasion effect inside the front and side plow blades results in scratching paint and exposing fresh steel to corrosion in a continuous process. The most exposed surface to abrasion is localized in the lower portion of the blades where the sand-loaded snow is compressed, accumulated and cast off to the side. A regular and periodical maintenance is therefore required to ensure a minimum of longevity and important periodic operations of sand-blasting, of protection coating and of painting are needed. Hence, important maintenance costs and a constant wear of the equipment due to corrosion are factors affecting present snowplow equipment.